1. Field of the Invention
The present invention relates to a fuel cutoff valve for shutting a passage between a fuel tank interior and the exterior, mounted on the upper part of the fuel tank, and particularly relates to the structure of the passage to the exterior.
2. Description of the Related Art
A fuel cutoff valve is disclosed in JP2009-168045A. The fuel cutoff valve is mounted on the upper part of the fuel tank, and is equipped with a cylinder shaped housing having a connection hole on the upper part of the housing, a float that is housed in a valve chamber inside the housing, and a cover which covers the upper part of the housing and forms a linking chamber, and makes an air exhaust port projecting from the cover for connecting to a canister. The fuel cutoff valve, by opening and closing the connection hole of the housing by the rise and fall of the float, ensures ventilation of the fuel tank to the outside, and also prevents the outflow of fuel within the fuel tank to the outside.
With the fuel cutoff valve, to prevent the outflow of liquid fuel to the outside, the passage from the connection hole to the air exhaust port has a barrier wall provided enclosing the connection hole, and is constituted by cutting out a portion of the barrier wall. With the ventilation passage, since a labyrinthine structure is created by the barrier wall, the ventilation resistance becomes large, in other words, the pressure loss become large, so the structure made it difficult for fuel vapor to flow smoothly.